For the purpose of preventing oxidation by oxygen and performing long-term storing of various goods tending to be affected by oxygen and accordingly deteriorated or degraded, typified by food, beverages, pharmaceuticals, medical supplies, cosmetics, metal products and electronic products, there have been used oxygen absorbing agents for removing oxygen inside the packaging containers or packaging bags containing these goods.
Recently, film-shaped oxygen absorbing agents being more easily handleable, applicable in wide ranges and extremely low in the possibility of accidental ingestion have been attracting attention, and many proposals have been put forward on the oxygen absorbing composition and the film structure of the film-shaped oxygen absorbing agents. From the viewpoint of maintaining the oxygen absorption performance of the film-shaped oxygen absorbing agent, it is desirable that the film-shaped oxygen absorbing agent be free from the occurrence of oxygen absorption when the film is formed, the film is processed into bags or the like and the film is stored; on the other hand, from the viewpoint of quickly exhibiting the oxygen absorption performance of the film-shaped oxygen absorbing agent when used, a film-shaped oxygen absorbing agent needing a trigger for initiating the oxygen absorption is desirable. A method has hitherto been proposed in which a photoinitiator is contained in a film containing, as an oxygen absorbing agent, a resin composition including a resin to be oxidized and a transition metal, and the oxygen absorption is initiated by using as a trigger the irradiation with ultraviolet ray (Patent Literature 1).
On the other hand, in the oxygen-absorbing resin composition containing a photoinitiator, the photoinitiator tends to migrate from the resin composition to the outside. Accordingly, when the resin composition is used as a packaging material, in particular, a food packaging material, the reduction of the migration amount of the photoinitiator is required. For this requirement, it has been proposed to use, as a photoinitiator having a smaller migration amount to the outside of the resin composition, a benzophenone derivative having a specific structure and being substantially non-extracting (Patent Literature 2 and Patent Literature 3).